What does annealing refer to in metalworking?

Annealing in metalworking refers to a heat treatment process that involves heating the metal to a specific temperature and then allowing it to cool slowly. This process is designed to relieve internal stresses that have built up in the material during previous processing stages, such as welding, machining, or casting. By relieving these stresses, annealing improves the ductility and toughness of the metal, making it less brittle and more workable.

The significance of stress relief in annealing cannot be overstated, as it allows the material to be more easily manipulated and formed into desired shapes without the risk of cracking. In addition to stress relief, the process can also refine the grain structure of the metal, leading to improved overall performance in terms of strength and durability.

The other choices focus on outcomes that are not directly related to the primary purpose of annealing. Increasing hardness generally refers to processes such as quenching or work hardening, reducing weight involves altering the material's composition or using different materials, and enhancing corrosion resistance pertains to treatments that typically involve coatings or alloying elements rather than the heat treatment process defined by annealing.